I'm a slow typer-- while I was banging away Dave beat me to it, but here it is better late than never..

Hey Riverbilly looks like you're having fun tying.

Sure you're 5 weight would be great for perfect for throwing a size 16--

Generally a 5 weight will easily throw flies size 6 or 8 down to as small as they make 'em, size 32. You can throw larger stuff too, but large wind resistant flies and poppers and/or big heavily weighted stuff would usually be easier to throw with a heavier weight fly rod.

A 5x tippet would be about right for the size 16 fly-- Generally I use a knotless tapered monofilament leader about as long as my rod (9' long) and add a short (about 2') section of tippet to the end of the leader-- that way you can change flies without chopping up your tapered leader too much.

There area couple different guidelines you can use to match fly size with tippet size-- the one that's easiest to remeber is hook size divided by 3 = tippet size--- so for a fly on a size 12 hook, size 12 / 3 = 4X tippet.

for your size 16, divided by 3 = 5X (since 5 is the closest to 5.333333)

That said, if all you have is 4x or 6x that doesn't mean you have to pack up and go home-- these are just guidelines

Tried the link above to no avail but here's one. I first saw this in a brochure from Cortland and soon after or before Orvis so the credit is to them I suppose: » Tippet To Fly-Size Chart - Fly Fishing & Fly Tying Information Resource Above that and hte divide rule above, keep in mind that when you use a bead head, a weighted fly or one that is aerodynamically hindered such as a Gurgler, or a Goddard caddis, the size should be adjusted a tad.